Nucleonic measuring apparatus with automatic fire safety radiation source shutter closing and locking means responsive to high temperatures for blocking the path of the shutter movement to open position

ABSTRACT

A nucleonic measuring gauge for cigarette tubing in which a housing contains a radiation source and has an aperture controlled by a sliding shutter, in which a U-shaped spring steel shutter lock is positioned in the path of shutter movement and has leaves which are held in an open position by a quantity of meltable material permitting the shutter to move between the leaves, and in which the spring leaves are stressed to close together behind the shutter blocking the shutter in a closed position upon occurrence of an abnormally high ambient temperature with the melting of the material.

O United States Patent 1 1 3,560,748

[72] Inventor Bernard W. Hatten 2,325,703 8/1943 Nute et al. 220/89(B)Columbus, Ohio 2,452,118 10/1948 Florence 220/89(B) [2]] App]. No.634,365 2,858,450 10/1958 I-Iolben l 250/83.3X(D) [22] Filed Apr. 27,1967 2,932,744 4/1960 Lehman 250/105 [45] Patented Feb. 2, 19713,338,255 8/1967 Exline et a1. 250/89X(B) [73] Assignee IndustrialNucleonics Corporation 1,662,863 3/1928 Mueller 292/327 a corporation ofOhio 1,908,241 5/1933 Heeren et a1. 292/327 2,103,743 12/1937 Doty292/327 54 NUCLEONIC MEASURING APPARATUS WITH Primry ExaminerRalphNilson AUTOMATIC FIRE SAFETY RADIATION SOURCE -Mor on J Frome SHUTTERLOS G AND LQCKING MEANS Attorneys-Marechal, Biebel, French and Bugg,William T. RESPQNSIVE TO H H M R R FOR Fryer, III, C. Henry Peterson andJames J. OReilly BLOCKING THE PATH OF THE SI-IU'I'I'ER MOVEMENT TO OPENPOSITION 7 Claims, 7 Drawing Figs.

[52] US. Cl 250/106, ABSTR A nucleonic measuring gauge f cigarette250/333, 250/105, 220/39 ing in which a housing contains a radiationsource and has an [51] Int. Cl GOlt l/I7 aperture controlled by aSliding Shutter, in which a U Shaped [50] Field ofSearch 250/83.3D,spring Steel Shutter lock is positioned in the path f Shutter 1068;220/898, 55.3, 47; 180/ 107; 2 2/ 7 movement and has leaves which areheld in an open position 70/440 by a quantity of meltable materialpermitting the shutter to 56 R f Cted move between the leaves, and inwhich the spring leaves are 1 e erences I stressed to close togetherbehind the: shutter blocking the UNITED STATES PATENTS shutter in aclosed position upon occurrence of an abnormally 1,914,250 6/1933 Gillen220/ 89(8) high ambient temperature with the melting of the material.

i 1 i I 15' I l I t i 16 18 l 12 L t I 2 j 2 45 I 2O PATENTED FEB 2'91:560.748

FIG-1 i L i 4o Ma! i 66 FIG-4 I I I 2 I t 6 18 73 I? 5 p54. 65 3x35 VENTR m o 50 7:; BERNARD w. HATTEN ATTORNEYS NUCLEONIC MEASURING APPARATUSWITH AUTOMATIC FIRE SAFETY RADIATION SOURCE SHUTTER CLOSING AND LOCKINGMEANS RESPONSIVE TO HIGH TEMPERATURES FOR BLOCKING THE PATH OF THESHU'I'IER MOVEMENT TO OPEN POSITION RELATED INVENTIONS The presentinvention relates to inventions disclosed in the copending applicationSer. No. 634,364, Filed Apr. 27, 1967, now abandoned of Bernard C.Holben and Richard E. Bach, Ser. No. 634,366, Filed Apr. 27, 1967 ofRichard E. Bach and Ser. No. 634,363, filed Apr. 27, I967 ofGeorge J.Trachevski, and Earnest A. Auborn, all assigned to the same assignee asthis invention and filed on even date herewith.

BACKGROUND OF THE INVENTION Compact nucleonic measuring gauges, such asthose used for measuring the weight or density of cigarette tubing forexample, have been provided with radiation source housings havingshutters which are operated by a suitable motor, such as by an electricrotary solenoid, for retracting the shutter and permitting the releaseof radiation from the nucleonic source. Examples of such measuringinstruments are shown in the U.S. Pats. of Radley et al. Re. No. 25,476of I963 and Dukes et al. No. 3,240,940 of 1966, both assigned to thesame assignee as this invention.

Normally such shutters are positioned between the source and a radiationaperture, and also arranged to close automatically upon thedeenergization of the controlling motor, such as by a retraction orclosing spring in or associated with the solenoid. Accordingly, when theradiation measuring device is deenergized, the shutter automaticallyreturns to its closed position. However, in the event of a fire or otherdisaster, it is important that the shutter remain in its closed positionto confine all radiation to the source housing and to assure theintegrity of the housing even during conditions of severe jarring orrapid accelerations or decelerations.

SUMMARY OF THE INVENTION The present invention relates to nucleonicgauging apparatus of the compact type disclosed in the above-mentionedRadley et al. and Dukes et al. patents, and more particularly tocompact, lightweight, and reliable apparatus for locking a shutter inits closed position in the event that certain predetermined andabnormally high temperature limits are exceeded. The invention employs aspring member which has oppositely positioned leaves or legs which arenormally spring biased together, but which are maintained in a separatedor open condition by reason of a quantity of meltable material, such assolder or lead, formed between the leaves of the spring. In the opencondition, the leaves form a clearance or gap through which the shuttermay pass as it moves from its closed toward its open position.

The lock of this invention occupies a minimum of space and is thereforeparticularly adapted for use where there are space limitations. It isalso of simple construction and is resistant to mechanical shock. Whenthe material melts, the spring leaves move together to close the gap,thereby clocking the shutter in the closed position. The subsequentrelaxing of the spring at even higher temperatures does not adverselyaffect the integrity of the lock. Shock loads tend to move both freeends of the spring in the same direction, and the spring is soconfigured and positioned so that some portion of the spring alwaysblocks the path of the shutter after the barrier material has melted.

It is accordingly an important object of this invention to provide anucleonic measuring instrument having a shutter lock in the form of afolded or a U-shaped spring which has oppo tely positioned leaves heldapart by a barrier of meltable metal, such as solder or lead, and whichleaves move together upon the melting of this material to form amechanical block preventing opening movement of the shutter.

These and other objects and advantages of the present invention will beapparent from the following description, the accompanying drawings, andthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical sectional view ofa radiation source and detecting unit incorporating a shutter lock ofthis invention, taken generally along the line l-l of FIG. 2;

FIG. 2 is a bottom plan view, partially broken away, of the nucleonicsource housing assembly taken generally along the line 2-2 of FIG. 1;

FIG. 3 is a vertical fragmentaq section through the housing assemblytaken generally along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary section through the housing assemblytaken generally along the line 4-4 of FIG. 2;

FIG. 5 is a vertical fragmentary section showing the shutter lock in theopen position;

FIG. 6 is a view similar to FIG. 5 showing the lock after it has beenactuated by the melting of the barrier material; and

FIG. 7 is an end view looking into the end of the lock and showing theshutter in section taken generally along the line 7-7 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a nucleonicmeasuring unit 10 includes a mounting base 11 on which is supported ablock 12 of shielding material. An ionization chamber detector 15 ismounted in superimposed relation on the block 12. A cylindrical passtube 16 is formed through the block 12, through which cagarette rod 17,or the like, may pass for measurement. The tube 16 is positioned inintersecting relation to a vertically aligned slot 18 formed in theblock 12. The slot 18 forms a passage through which radiation passesfrom the source to the detector 15.

A nucleonic radiation housing assembly is indicated generally at 20 inFIGS. 1 and 2 and is mounted on the bottom surface of the block 12. Theassembly includes a source 22 mounted in a slot 22 in a hinged sourceholder 23 so that when the holder 23 is closed, as shown, the source 22is positioned in alignment with the slot 18. A source holder retainerplate 24 retains the source holder 23 in its closed position.

The source holder 23 and the retainer plate 24 are mounted on a retainerassembly and shutter guide plate 25 which is retained on the lowersurface of the base plate 12 by four screws 27 (FIG. 2). The plate 25defines an aperture or window 28 which is in substantial alignment withthe slot 18, and is spaced from the bottom surface of the block 12 by asimilarly apertured phenolic spacer 30.

A radiation shutter 35 is guided for sliding movement between theretainer plate 25 and the phenolic spacer 30. The plate 25 is notched at36 as indicated in FIG. 4 to provide a guide channel for the shutter 35.The shutter 35 is thus guided for sliding movement between an openposition where it exposes the window 28 and a closed position, as shownin FIGS. 2 and 4. In the closed position it effectively closes theaperture formed by the window and blocks the escape from the housing ofany radiation from the source 22.

Means for opening and closing the shutter includes a rotary,spring-return solenoid 40 mounted on an L-shaped support bracket 40'above the detector 15. The rotary motion of the solenoid 40 istransferred to sliding movement at the shutter by means of a solenoidarm 41 which is forked at its end to engage a pin 42 mounted on an arm43. The arm 43 is clamped to a shaft 44, and the shaft 44 is rotatablysupported at its upper end on the support 40', and at its lower end inthe block 12.

A depending portion of the shaft 44 extends downwardly through the block12 and supports an arm 45 at its lower end. A depending crank pin 46 onthe arm 45 is received within an elongated slot 47 (FIG. 2) formed inthe shutter 35, so that turning movement of the arm 45 affects slidingmovement of the shutter 35 in its guideways. For further details of theconstruction and operation of the device reference may be had to theRadley et al. and Dukes et al. patents previously mentioned.

Means for locking the shutter 35 in the closed position upon theoccurrence of an abnormally high temperature includes a generallyU-shaped lock 50 formed of leaf spring material. The lock 50 is thusformed with an integral back 51 and a pair of generally oppositelypositioned leaves or legs 52 and 53. The spring legs are slightly angledinwardly toward each other and terminate in outwardly turned, integralflanges 54 and 55. The spring material from which the lock is made isstressed so that the legs 52 and 53 are normally urged together, but aremaintained in spaced relation to each other by a filling or barrier 60of meltable material which is cast in place between the legs 52 and S3and against the back 51 partially filling the space between the legswhile defining a gap 62 at the leg terminal ends and at the flanges 54and 55.

The material 60 may be made of any suitable composition which melts at apredetermined high temperature, such as solder or lead. For example, itmay be formed of a solder composition of approximately 75 percent tin3.5 percent silver and 1 percent antimony which has a eutectic meltingtemperature of approximately 430 F. However, other metal alloys may beused which have substantial resistance against cold flow, to retain theshape of the lock 50 and to prevent creeping of the leaves over extendedperiods of use at temperatures below the eutectic temperatures.

The opposite legs of the lock 50 are accordingly held in normally spacedapart relationship defining the space or gap 62 therebetween, as shownin MG. 5. The lock 50 is positioned so that an edge portion of theshutter must pass through the gap 62 in the initial movement from itsclosed to its open position. The lock 50 is held in position on theblock 12 by a suitable cap screw 65 extending through openings formed ineach of the legs 52 and 53 and threaded into a tapped hole formed at thebottom of the block 12. The lock 50 is symmetrical so that orientationwith respect to the head of the screw 65 is not required.

In the operation of the invention, in the event that an abnormally hightemperature occurs such as would be caused by a fire, the shutter willbe closed by the removal of, or the failure of, power to the rotarysolenoid 40. To assure that the solenoid is deenergized, power to thesolenoid may be controlled by a temperature sensitive fuse 66, such asthe WKR, Buss leaf spring type manufactured by Bussman ManufacturingDivision of McGraw-Edison Company of St. Louis, Missouri, which willinterrupt the flow of current to the solenoid when the ambienttemperature reaches approximately 200 F.

The shutter 35 will then be returned to its closed position. Thereafter,if the ambient temperature should continue to rise to the eutectic rangeof the blocking material 60, the material will melt permitting thespring legs or leaves 52 and 53 to close the gap 62 by moving togetherbehind and in blocking relation to the shutter, substantially as shownin FIG. 6, thereby preventing shutter movement into its open positionand effectively blocking it in the closed position. The outwardlyextending end portions 54 and 55 assure the effectiveness of the blockeven though some movement of the lock may occur as a result of shock orvibration. Further, the shutter lock of this invention will remaineffective even though the temperature may continue to rise to the pointwhere the temper of the spring material is lost.

It will therefore be seen that this invention provides a compact,dependable, and shock-resistant barrier or shutter lock which operatesto lock closed a movable shutter of a nucleonic measuring gauge upon theoccurrence of abnormally high temperatures, such as would occur during afire. It

retains its effectiveness over extended periods of normal usage and issubject to very little, if any, creepage when operated in a temperatureenvironment below the melting or eutectic temperature range of thematerial 60.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apposition, means for lockingsaid shutter in its said closed position upon the occurrence of anabnormally high ambient temperature including a generally U-shapedspring member having opposite legs movable between a spaced apartposition under which said spring material is stressed defining a spacetherebetween permitting movement of said shutter therethrough betweenits said positions and a closed position blocking the movement of saidshutter toward its said open position, and a normally rigid materialpositioned in said spring member between said legs holding said legsinsaid spaced apart position and being meltable in response to said highambient temperature for releasing said legs for movement into their saidclosed position. i

2. The instrument of claim 1 in which said rigid material is a eutecticmetal alloy cast in said spring member and partially filling the spacebetween said legs.

3. The instrument of claim 1 in which said legs terminate in outwardlyturned ends for blocking said shutter in the event of movement of saidspring member.

4. The instrument of claim 1 in which said spring member is formed fromflat spring material.

5. A nucleonic radiation energy-measuring instrument having a source ofnuclear energy and incorporating a temperature-responsive safety lock inwhich a shutter member is mounted for movement between a retractedposition defining an opening for radiation measurement purposes and aclosed position effectively confining radiation from said source, theimprovement in shutter-locking mechanism comprising means defining alocking spring having portions positioned adjacent said shutter andmovable between a first position defining a clearance gap permittingmovement of the shutter therepast between its said positions and asecond position in which said. portions are in interfering relation withsaid shutter blocking the movement of said shutter from its closed toits open position, said spring being stressed to move said portion intoits said second position, and a barrier of a normally rigid meltablematerial supporting said spring portions in their said first positionand being meltable upon the occurrence of an abnormally high ambienttemperature to permit said spring portions to move to their said secondposition.

6. The locking mechanism of claim 5 in which said movable portionscomprise two leaves of a generally U-shaped spring and said clearancegap is defined as the space between the ends of said leaves.

7. The locking mechanism of claim 6 in which said barrier comprises aeutectic metal alloy cast within and partially filling the space betweenthe said leaves.

1. A nucleonic radiation-measuring instrument comprising a housingenclosing a source of nuclear radiation and having an aperture forreleasing radiation from said housing for measurement purposes, ashutter for said aperture, means guiding said shutter for movementbetween an open position to release radiation from said aperture and aclosed position effectively confining the radiation within said housing,motor means for moving said shutter from said closed position to saidopen position, means for locking said shutter in its said closedposition upon the occurrence of an abnormally high ambient temperatureincluding a generally U-shaped spring member having opposite legsmovable between a spaced apart position under which said spring materialis stressed defining a space therebetween permitting movement of saidshutter therethrough between its said positions and a closed positionblocking the movement of said shutter toward its said open position, anda normally rigid material positioned in said spring member between saidlegs holding said legs in said spaced apart position and being meltablein response to said high ambient temperature for releasing said legs formovement into their said closed position.
 2. The instrument of claim 1in which said rigid material is a eutectic metal alloy cast in saidspring member and partially filling the space between said legs.
 3. Theinstrument of claim 1 in which said legs terminate in outwardly turnedends for blocking said shutter in the event of movement of said springmember.
 4. The instrument of claim 1 in which said spring member isformed from flat spring material.
 5. A nucleonic radiationenergy-measuring instrument having a source of nuclear energy andincorporating a temperature-responsive safety lock in which a shuttermember is mounted for movement between a retracted position defining anopening for radiation measurement purposes and a closed positioneffectively confining radiation from said source, the improvement inshutter-locking mechanism comprising means defining a locking springhaving portions positioned adjacent said shuTter and movable between afirst position defining a clearance gap permitting movement of theshutter therepast between its said positions and a second position inwhich said portions are in interfering relation with said shutterblocking the movement of said shutter from its closed to its openposition, said spring being stressed to move said portion into its saidsecond position, and a barrier of a normally rigid meltable materialsupporting said spring portions in their said first position and beingmeltable upon the occurrence of an abnormally high ambient temperatureto permit said spring portions to move to their said second position. 6.The locking mechanism of claim 5 in which said movable portions comprisetwo leaves of a generally U-shaped spring and said clearance gap isdefined as the space between the ends of said leaves.
 7. The lockingmechanism of claim 6 in which said barrier comprises a eutectic metalalloy cast within and partially filling the space between the saidleaves.